Survey parties in 1905 and 1906 were further studied by the subsequent expeditions of the National Geographic Society. The fullness of the description of the Yakutat Bay region, therefore, depends not merely on the work of the seasons from 1909 to 1918, but to a very large degree, on the studies of 1905 and 1906. The investigations of these five seasons have developed a series of interesting and important results, the statement of which can be adequately made only by making free use of the work of the previous expeditions. This has, therefore, been done, not in the form of direct quotation of our previous publications relating to the expeditions of 1905 and 1906, but in such abstracts as have seemed necessary to the clearness of discussion of the problems which the Yakutat Bay glaciers present. This report, in so far as the Yakutat Bay region is concerned, is the summary and discussion of the results of five seasons of work, not of the seasons of 1909, 1910 and 1913 alone.
The description of conditions in Prince William Sound and on the lower Copper River is almost entirely new. The discussion of the glaciers of Alaska in Chapter I of this book, and of the glaciers and glaciation of Prince William Sound and the Lower Copper River, Chapters XII to XXIII, is wholly the work of the junior author. The senior author, however, with his greater experience and wide observation of glaciers in Greenland, Norway, Spitzbergen, and the Alps, saw a great deal in the few days he spent in eastern Prince William Sound and on the lower Copper River in 1909. Accordingly he was able to advise in the arrangement of the materials of Chapters XII to XXTTT and generously gave much time and thought to the criticism of the portions of manuscript—all but the last three chapters—which were completed before his lamentable death on March 21, 1912. He also wrote parts of the pages on the Comparison between Yakutat Bay and Prince William Sound. The junior author's debt to Professor Tarr, as teacher in lecture room, laboratory, and field, and as councillor and friend can never be adequately acknowledged.
Many of the photographs used as illustrations in this book were taken by the authors and by our photographers—0. D. von Engeln in 1909, and R. B. Byers in 1910. We" are deeply indebted to both of them for their excellent photographs and for splendid service in the field in Alaska, where the exposing and developing of photographs have especial difficulties. In the Magazine for January, 1910, the former of these men described some of these difficulties. We have also used a few photographs taken by the late Professor I. C. Russell of the University of Michigan and Mr. H. G. Bryant of Philadelphia, by members of the Harriman Expedition, of the United States Geological Survey, and the International Boundary Surveys, by engineers of the Copper River and Northwestern Railway, and several Alaskan photographers, as acknowledged specifically in the legends of the plates.
Among the text figures are several based upon manuscript maps of Prince William Sound, supplied by Professor U. S. Grant of Northwestern University. Some of the cross-sections of the fiords were drawn by Mr. E. P. Bean of the University of Wisconsin, who has also been of great service in assisting with the proofreading and with making the index of tfrip book.
We were thoroughly equipped for glacier study during each season in the field, thanks to the large appropriations by the Research Committee. For assistance in arranging and carrying out our plans in Alaska we are under deep obligations to the companies and institutions whose contributions are acknowledged elsewhere in t.Tiia book, as well